Alloy



Patented Dec. 29; 1942 ALLOY Albert A. Smith, Jr., Metuchen, N. J., assignor to American smelting and Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application February 13, 1942, Serial No. 430,805

2 Claims.

This invention relates to lead alloys and more particularly to lead-tin-silver alloys. products of the invention are especially useful as solders but may be utilized for other purposes where it is desired to employ a metal having the physical characteristics of the lead alloys as hereinafter described. 1

Lead-silver solders have been known for many years but, because of their relatively high melting temperatures and poor spreading properties, they have not been extensively used. I have discovered, however, that by alloying tin with the lead-silver alloys the aforementioned disadvantages are substantially overcome while certain beneficial properties of the binary alloy are retained.

Broadly speaking, the present invention or di s.

, covery may be said to provide a ternary alloy of tageous physical properties.

lead, tin and silver having certain highly advan- In the following table there is listed some of the significant physical characteristics of these alloys which have been determined. For comparison, corresponding test values are shown for some conventional tin-lead and silver-lead solders. Carefully standardized testing technique was employed in each instance to obtain the comparative test results shown:

The alloy One of the unexpected improvements resulting from the introduction of silver in lead-tin solders is manifested by the increased resistance to creep, as shown in the table.' Further, with the addition of a relative small amount of silver, the tin content can be materially lowered without producing adverse effects. This is of great importance where it is desired to use a minimum content of tin. The preferred lead-tin-silver alloy compositions of my invention are shown in the table. In general, however, the alloy compositions may comprise from 5% to 40% tin, 0.5% to 5.0% silver with the balance lead. Small amounts of antimony, i. e. from 0.25% to 3% may be present or added, particularly where a high tensile strength alloy is desired.

From the data given, it will be appreciated that the ternary alloys of this invention possess and exhibit properties which make them suitable for various uses other than solders, and such other uses are intended to come within the scope of my invention as defined by the appended claims.

What is claimed is:

l. A relatively low melting point alloy composition having high tensile strength and resistance to creep which consists principally of lead, tin and silver, said constituents approximating from 5% TABLE Some properties of soft solders v Creep rate in per cent per year Com sition 1: cent Bond P W Licguidus s'llensilli1 strength Sfpread at C.

' O. g of lapped 3 g Pb Sn Ag 200 psi 400 psi 600 psi 800 psi 60 238 6660 6270 1. 30 10. 9 92 300 97. 5 2. 5 304 4980 3740 0. l9 0. 10 0. l5 0. 50 95 5 375 4015 4340 0. 20 0. 18 0. 22 0. 95 5 312 4800 4000 0.22 92.5 5 2.5 309 4860 4300 0.30 90 10 208 4850 4960 0.27 2.5 87. 75 10 2. 25 1 200 4050 5000 0. 41 2. 3 8. 0 80 20 275 4940 5680 0. 37 6. 7 18. 7 78 20 2 267 5620 5550 0.57 70 30 257 5390 5770 0. 83 69 30 1 1 251 8810 l 5620 0. 86 4 I Determined in this investigation from cooling curves.

Norm-Bond and spread tests were-made on copper sheet. Tensile and creep tests were made on chill cast strips of the alloys.

The ternary alloys of lead-tin-silver offer a variety of solders which have somewhat higher melting points than the ordinary 40-60 (Sn-Pb) solder but exhibit good spreadingand bond strength properties. Silver added to low-tin solders decrease the liquidus temperature from 6 to 8 C. and markedly improves the spreading properties without appreciably affecting the bond strength.

ALBERT A. SMITH, JR.

Disclaimer I Metucheri, N. J. "ALLOY:

2,306,667.Albert A. Smith, J12,

1942. Disclaimer filed Oct. 27, 1949, by the ass and Refining Company.

Hereby enters this [Oifim'fil Gazett disclaimer to claim 2 of said patent. a December 20, 1949.]

gnee, American smelting 

